From 937e0f30e601f935339beb29f067de0cff431b09 Mon Sep 17 00:00:00 2001
From: "C. Torres" <torr.c@mailgw.com>
Date: Sun, 15 Dec 2024 21:52:36 -0300
Subject: [PATCH] Implement file reply serving mode

Implement a serving mode where a file is sent as reply to every
websocket message received.

Signed-off-by: C. Torres <torr.c@mailgw.com>
---
 ws/file_reply.go | 63 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 ws/file_reply.go

diff --git a/ws/file_reply.go b/ws/file_reply.go
new file mode 100644
index 0000000..e76cc71
--- /dev/null
+++ b/ws/file_reply.go
@@ -0,0 +1,63 @@
+package ws
+
+import (
+	"fmt"
+	"io"
+	"io/fs"
+	"os"
+	"wssrv/log"
+
+	"github.com/gorilla/websocket"
+)
+
+func sendFileReply(con *websocket.Conn, fileNa string) error {
+	var (
+		err       error
+		msg, data []byte
+	)
+
+	if data, err = os.ReadFile(fileNa); err != nil {
+		return fmt.Errorf("unable to read file '%s': %v", fileNa, err)
+	}
+
+	for err != io.EOF {
+		if _, msg, err = con.ReadMessage(); err != nil {
+			return fmt.Errorf("unable to read from websocket on '%s': %v", con.RemoteAddr(), err)
+		}
+		fmt.Printf("(%s): %s\n", con.RemoteAddr(), msg)
+
+		log.Info.Printf("sending file '%s'", fileNa)
+		if err = con.WriteMessage(websocket.TextMessage, data); err != nil {
+			return fmt.Errorf("unable write on websocket on '%s': %v", con.RemoteAddr(), err)
+		}
+	}
+
+	return nil
+}
+
+// SendFileReply sends a given file in the websocket as a reply to every
+// message received.
+func SendFileReply(con *websocket.Conn, fileNa string) error {
+	switch {
+	case con == nil:
+		return fmt.Errorf("nil connection parameter")
+	case len(fileNa) == 0:
+		return fmt.Errorf("empty file parameter")
+	}
+	var (
+		err  error
+		stat fs.FileInfo
+	)
+
+	if stat, err = os.Stat(fileNa); err != nil {
+		return fmt.Errorf("unable to check metadata for file '%s': %v", fileNa, err)
+	}
+	if !stat.Mode().IsRegular() {
+		return fmt.Errorf("file '%s' is not regular")
+	}
+	if stat.Mode()&0444 == 0 {
+		return fmt.Errorf("file '%s' is not readable")
+	}
+
+	return sendFileReply(con, fileNa)
+}